Samuel R Delaney is awesome, at least based on the two books of his I've read ("Babel 17", though apparently the linguistics in that is more rule-of-cool than accurate) and Star in my Pocket like grains of sand. And after that last one I'd have been somewhat surprised if he wasn't gay, I'm hard pressed to think of any scifi I've read with that many references to gay sex that wasn't slash :)(*)

(*)Goes into mental tangent about the rarity of GLBT protagonists in sff
EDIT: Huh Homosexuality in speculative fiction on Wikipedia is interesting.